1. Field of Invention
This invention relates to an improved metallurgical vessel and a method of employing the same for improving the efficiency of use of high temperature metallurgical vessels and more particularly relates to providing for an increase in the useable quantity of molten metal withdrawn from such vessels.
2. Brief Description of the Background Art
As will be recognized by those skilled in the art, in high temperature vessels such as molten steel ladles, one problem heretofore encountered relates to preventing slag from contaminating or otherwise being mixed with the relatively pure steel when it is being withdrawn from the vessel. Since slag is less dense than the molten steel, the slag tends to rise and accumulate on top of the underlying steel. If a pouring orifice is provided in the bottom of the vessel, relatively uncontaminated molten steel can be withdrawn simply by opening the orifice to permit the liquid steel to exit therethrough. However, when the liquid surface falls until it is near the bottom of the vessel, pouring must stop before slag exits along with the remaining steel; and thus a quantity of steel remains in the vessel and is unusable. In order to keep this unusable quantity of molten metal as small as practicable, it has become customary to provide sloping bottoms with a low point at or near the edge of the vessel where a pouring orifice is positioned. However, this has brought about a relative inefficiency in refractory brick installation and utilization.
A variety of designs and processes have been proposed to improve efficiency of metallurgical vessels such as, for example, molten steel ladles.
U.S. Pat. No. 5,196,051 (Heaslip et al.) discloses ladle bottom geometries having sloping surfaces whereon there are positioned pluralities of castellations for reducing vortices that otherwise might entrain slag or other impurities in the exiting liquid as the ladle is emptied.
U.S. Pat. No. 4,746,102 (Gilles et al.) discloses a multi diameter drain hole design and a drain hole closing valve in the bottom of a metallurgical ladle for reducing the yield loss from the metallurgical ladle wherein the metallurgical ladle has liquid metal having a layer of slag on the liquid metal.
In spite of this background material, there remains a very real and substantial need for an improved metallurgical vessel for increasing efficiency of refractory brick utilization and/or for increasing the quantity of usable molten metal such as, for example, steel, that may be poured from a metallurgical vessel such as, for example, a ladle. It will be appreciated by those persons skilled in the art that because of the large sizes and holding capacities of typical ladles and the volume of steel normally carried therein, even a relatively small percentage increase in volumetric efficiency translates into a large absolute volume and correspondingly large cost savings providing substantial economic advantages.